Spring and method of making it



Feb. 25, 1941. E. H. PIRON SPRING AND METHOD OF MAKING IT Filed May 27, 1958 INVENTOR. 2 m 75 7 0w? ATTORNEY.

1 P Fig. is a view similarto Fig. 2 showing a i'urs Patented Feb. 25, 1941 PATENT OFFICE ammo m METHOD or mxmo rr Emil HQPiron, New York, N. Y.,- assignor to Transit ltesearchcorporation, a corporation or New York Application May 21', 1938, sem1n .z1o,a1s

19 Claims. (circa-s3) This invention relates to elastic springs made of one or several masses of elastic material such as rubber or the like surface bonded to stiff parts some of which are load imposing and load receiving members usually made of metal. The more usual form is where the stiflor metallic partsare concentric andcylindrical in shape and are separated from adjacent parts by elastic material which offers resistance torelative movement of W the metal parts in shear or in torsion and in compression. l a

The principal object of this invention is to provide an improved spring which is more economical to fabricate together with an improved method of making this spring.

More particularly it is the object to provide a spring composed-.01 alternatecylinders of metal 3 and elastic material, themetallic cylinders being capable of expanding or shrinking their diameter under radial forces to permit compression oi the elastic material between them.

A f urther object is to provide a spring as above described which will have improved stillness against relative tilting of the metallic parts, such movements being ordinarily undesirable in a springing system. i

Specifically it is an object to provide a spring,

as above described, in which the metallic parts are each split parallel to their axis, the split or slot being of material width so as to permit expanding of the cylinder by widening of the slot or l to permit contraction of the cylinder by narrowing of the slot. To make this possible yet prevent excessive local stress in theelastic material in the 5 immediate vicinity of the split, air spaces are provided in the rubber along said slots.

Other objects and advantages will become more fully apparent as referenceis had to the ac. companying drawing wherein my, invention is il- 0 lustrated, and in which Fig. 1 Iis a longitudinal diametric section through a mold in which my improved spring is being made, taken along the line l-l of Fig. 2, Fig. 2 is a horizontal section taken along the line 22 of Fig.1, s

Fig. 3 is a top or bottom plan view of a complete spring in,a retainer, l a

a Fig. 4 is a top or bottom plan view of a medi fled tormof spring, 1 a

ther modified form of spring in theprocess oi manufacture, 1 i

Fig. 6 is a longitudinal diametric view of the finished spring of Fig. 5, and

Fig. '7 is a top or bottom plan view of the spring or F a. 6- l l l More particularly ll indicates a mold which may be constructed conveniently of two parts 1/ and 3 which, when assembled, form a cavity havingtwo concentric. cylindrical or substantially cylindrical peripheries between which my improved spring is made. a e

The mold is filled with spring material composed of opposite cylindricallayersof metal 19 and. rubber compound 5, or equivalent material, to be vulcanized and surface bondedthereto, the metallic layers 4 extending outwardly beyond the rubber compound for extension into, grooves i formed into the two mold parts 2 and ,3. x The metallic layers each have a longitudinal. section omitted "which is to say that they are each longitudinally slotted, and the rubber adjacent the slot on each side thereof is forced away therefrom by pins I which areinsertedbetween the edges of a each slot before the :mold is assembled on the spring materials. The slots and pins of one layer are preferably peripherallyoffset from those of adjacent layers to increase the stiffness of the spring against tilting. The mold is then subject- 2: ed to heating until the rubber is vulcanized and cured to the metal-layers whereupon the spring is removed from the mold and the pins removed from their positions in the spring. The spring is I subjected to radialoompression when assembled 30 for operation, the assembly consisting of a load imposing and a load receiving membereither of which may be the internal or external member, the numeral Ill here, designating the external member and the numeral 5 the internal member. The members 9 and Ill arein the form otcylinders and in order to maintainradialcompression on the spring the inside diameter of the member 9 may be smaller than the outside diameter of the springas it comes from the mold so that there must be a reduction in the circumference of each metallicand rubberlayer for insertion into themember 9, thus reducing the width of the slot in each metallic layer together with the air gap in the rubber adjacent each slot; or the inside 5 member, Iii may be larger in outside diameter than the smallest metallic layer 5 so that ,upon insertion therein all, layers will be radially expanded thus widening the slots in the ,metallic layers and causing distortion of the shape of the 5g air spaces adjacent the slots. ,In the event that the direction of expansion is known, the slot of the inside or of the outside metallic" layer-need not be provided, Fig. 4 illustrating a spring in which it is contemplatedthetthe compressien will always be imposed outwardly and hence the outside metallic layer is a continuous cylinder.

In Fig. 8- the slot has been substantially reduced. Hie-dotted lines I l indicate the size of the original slots and air gaps. This figure illustrates the preferred form since the'spring will adjust itself to commercial tolerances of the member it is expected to fit even though the direction of the imposition of compression is known before manufacture. The inside and outside layera 4 are both slotted.

In Figs. 5, 6 and 7 a spring is illustrated in which the pins 1 have been replaced by a single plate I! which forms a slot I3 through all rubber layers la and which passes progressively. through the slots ll of the metallic layers 4a. This plate I! is interposed as the materials are being inserted in the mold in. After vulcanizing and curing, the plate is removed and the spring is ready for assembly with load imposing and load receiving members in the manner previously described.

This spring, also, may be made with the inner orouter metallic layer solid for the purposes hereinbefore describedFigs. 6 and 7 fllustrating the inner layer as being a complete cylinder.

It will be realized that when compression is imposed the layers may contract or expand uni formly into cylinders of different sizes or they may assume a somewhat oval or otherwise outof-round shape. In order to correct for an outof-round condition the mold may be made out-ofround, 'if desired. The stlfiness of metal has considerable bearing on the exact technique to be followed.

In all forms, the metallic cylinders preferably, but not necessarily, have greater length than the adjacent elastic cylinders.

What I claim is:

i l. A spring comprising a multiplicity of alternate layers of still material and elastic material, said layers of stiff material which are disposed between the elastic material being of substantially cylindrical form with a normally open single slot extending from top to bottom thereof whereby said layers are radially expansible and contractible to equalize compression throughout the multiple elastic layers.

2. A spring comprising alternate substantially cylindrical layers of rubber or' its equivalent and metal, some of said layers of metal being of substantially cylindrical form with a portion of the circumference thereof removed whereby they may .expand or contract across any diameter in the 'ipresence of unequal compression conditions in the elastic layers thereby to enable equalization of compression in the several elastic layers.

3. A spring comprising alternate substantially cylindrical layers of rubber or its equivalent and stiff material, at least someof said layers of still material being slotted from top to bottom forming two edges movable toward and. away from each other under inwardly and outwardly directed'radlal forces, respectively, resulting from unequal compression of rubber layers adjacent thereto to equalize compression therein, the

layers of rubber being recessed adjacent said edges thereby preventing overstressing of said rubber between said edges when said stilt-layers are compressed to close or to reduce the width of said slot.

4. A spring comprising alternate cylindrical layers of stiff material and elastic material surface bonded together, said layers of still material being of original cylindrical shape and slottedparallel to the axis thereof, and means imposing substantial radial compression on all said layers in final assembly, the size of the slots in said layers of still material being adapted to change cylindrical layers of still and elastic materiaL.

said layers of stiff material each having a single slot from top tobottom, said layers of elastic material each having a frusto-conical shape at its top and together forming a composite substantially frusto-conical exterior shape for the top of the spring, said stiff material being expansible and contractible-in the presence of unequal radial compression in the elastic layers to cause equalization of radial compression in the elastic layers. I

6. A spring composed of alternate substantially cylindrical layers of stiif and elastic material, said layers of stiff material each having a single slot from top to bottom, each slot being normally open whereby said still material may expand and contract radially, said layers of elastic material each having a frusto-conical shape at its bottom and together forming a composite substantially frusto-conical shape for the bottom of the spring.

7. A spring composed of alternate substantially cylindrical layers of stiff and elastic material, said layers of stiff material each having a single slot from top to bottom, each slot being normally open whereby said stifi material may expand and contract radially, said layers of elastic material each having a frusto-conical shape at its top and together forming a composite substantially frusto-conical exterior shape for the top of the spring, said layers of elastic material also having a frusto-conical shape at its bottom and together forming a. composite substantially frusto-conical shape for the bottom of the spring.

8. The combination as set forth in claim 7 wherein the inclination of the top and bottom are substantially different. I

9. A spring composed of alternate substantially cylindrical layers of stiff and elastic material, said layers of still material being slotted from top to bottom, each slot being normally 'open whereby said stifi material may expand and contract radially, and said layers of stiff material being progressively oflset with respect to each other longitudinally thereof, said layers of elastic material having inclined exposed surfaces to accommodate themselves to the positions of said still layers.

10. A spring composed of alternate substantially cylindrical layers of stiff and elastic material, said layers of stiff material being slotted from'top to bottom, each slot being normally open whereby said stiif material may expand and contract radially, and extending substantially beyond said layers of elastic material.

11. A spring composed of alternate substantially cylindrical layers-of stiff and elastic material, said layers of stiff material being slotted from top to bottom, each slot being normally open whereby said stifi material may'expand and contract radially, and of substantially greater length than said layers of elastic material where- ,by they project substantially beyond said layers the still material and grooves in the elastic material parallel to and in register with said slots.

13. A spring composed of alternate layers of still and elastic material, each of said layers being cylindrical and interruptedin its circumference whereby each may be contracted and expanded.

14. A spring composed of alternate substantially cylindrical layers of stiff and elastic material, the stifl cylindrical layers each having a single normally open radial slot interrupting the cylindrical form of each thereof, and the elastic material being grooved adjacent said slots and out '01 contact with the edges thereof.

15. A spring composed of alternate substantially cylindrical layers of stiff and elastic material, each of said layers being radially slotted with a single normally open radial slot and with all slots thereof aligned.

16. A spring composed of alternate substantially cylindrical layers of stiff and elastic material, at least one of the boundary layers thereof being continuous, the remainder of said layers being circumi'erentially interrupted.

17. A spring composed of alternate substantially cylindrical layers of stiff and elastic material, the inside layer thereof being continuous, the remainder of said layers being radially slotted from top to bottom. 1

18. The method of making a spring which consists in slotting a plurality of metallic cylinders of progressively increasing diameters, in arranging said cylinders concentrically, in placing spacing means in the slots of the cylinders, in interposing elastic material between said cylinders, in vulcanizing said elastic material to said cylinders, and in removing the means which hold said edges in spaced relation.

19. The method of making a spring which consists in slotting a. plurality of metallic cylinders of progressively increasing diameters, in arranging said cylinders concentrically, in interposing elastic material between said cylinders, in inserting spacer means of greater thickness than the thickness of said metallic cylinders in the slots, in vulcanizing the elastic material while surface-bonding it to said metallic cylinders, and

r in removing said spacer means.

Em. H. PIRON'. 

